Core former for making ducts



Jan 10, 1939. OROURKE.

CORE FORMER FOR'MAKING DUCTS Filed Aug. 1, i936 lNVENTOR V g Y 0 IR\ ag 1. ATTOR Patented Jan. 10, 1939 UNITED STATES PATENT OFFICE 11 Claims.

This l invention relates :to H apparatus for forming hollowmolded-:bodiesssuch as concrete ducts. This inventionrelatesparticularlyitoa core former adapted ,to form-the vcore ofiarhollow molded body 'suchuas a duct made of concrete.

:Heretoforeihollow bodies such as Iducts, pipes andvthe likei'have beenproduced usingrapparatus whichcomprises a vertical mold adapted to form.tthe rexternal surface of abodysuoh as a duct and La core former forcompacting andtroweling moldable imaterial such :35 concrete within ,the'mold .so as tolproduce az'hollow core. The: core former in apparatus of"this character has'been mounted oniarotatabIe shaft and has included acylindri- .;s "cal ihead havingaapproximately the diameter of thecorewhich isvttmbeformedin thecompleted duct. Means have:.been;providedforrotating the shaftandzheadn an'dzfor elevatingthe head fromthelbottom ofthe molditortheitop while the shaft is being. rotated.

Intapparatus heretoforemanufactured, the core formerrhas1taken-tmanydifferent forms. Generally; the core "former includesone. or more camshaped. members .zattached to: the r. shaft above the cylindrical head,.the cam surface presented-by the: cam shaped member v havingnits radiusfrom i the axis of the: shaft become increased until the maximum radiuscorresponds tozthe radius from the axis-of :theshaftirofttheperipherylof cylinzi-J drical head. Likewise, agitators 'have-beenat-'tached to the shaft-aboveithe core formerso as to distribute moldablevmaterial such as wet concrete above the cam shaped troweling member.The present invention is 1 especially applicable to the: manufacture-of:ductsv having a cylindrical -hollowcore and external. surfaces disposedat an anglewith respect to each other as is the casefor example whenthecross section of :the external surfaces forms a square (such ducts being.re- "ferred to herein as square ducts). Prior to this invention Iencountered serious-difficulties in the manufacture ofsquare ducts. Inusing apparatus heretofore employed, I foundthat the concrete at thecorners of the molds was compacted more i 45 looselyrthan in the thinlayer of concrete between the central hollowcoreand the mid portionofthewalls of the "duct. This was verydisadvantageous as the corners of theducts crumbled and theiducts were not acceptable. Many.,differenttypesofv core 50 formers including cam .shaped v troweling members,agitators-and the like, weretried bymebut the percentage ofunsatisfactory iducts remained as high as 50%. Forlsome time it appearedthat the manufacture of square ducts using machinery 1155 of the generalcharacter hereinabove referred a to r. tionejdi that; the mixtureofcementitious material randjfiller which is used in making concrete ducts15 is quite dryeandithatfiit must be very highly com-;pactedin:vorderqtmset properly to form a duct which ;;has the requisitestructural strength a throughoutqall portions thereof.

vi Featuresaofpthis invention relate to the manner inawhichqagspiral;blade-has; been combined with acam shapedqcompactor and .with otherelements of thecore; former. :Fromonepoint of view, it is aifeatureqofthis inventionthat a. spiral blade ifixedptoarotatable-shaftis-carrieddown so as to ibesinvenfdwise juxtapositionwiththe end of the icamicompactor. :Qther-features'of this inven- :tionrrelatezt-o; the .relative positions of r the spiral ;b1ade; and :thecam -compactor and to the form characteristics;ofithese parts.:Fromanother point of view, other features1of thisrinvention relatellOzthe distribution of the sp ral blade between a vblade part andvea'xwinglmember (to be defined therein below). LStill potherifeaturesofthis inwventionrelate toithexmanner in which' the blade parmand' wingare mounted, relative: to each othersaHdMt-OitheiCYJiHdI'iCfllTfOl-IOWGI' so as to permit :adjustment ofssome-relationships while retaining other relationships. Thusyforexample, the relationship of the blade portion of the wing mem- 40 herto--the blade of 'the blade part can be maintained while the ,cam-surfacepresented by the wing member can be adjustedlaterally relativeto the shaft according tothis invention.

Further features, purposesand advantages of 4 this invention will beapparent inconnection with the illustrative embodiment ,of .thisinvention shown in ,theiaccompanying. drawing, vwherein- Fig.1 1 isa-side view'partly in section showing a 5 core: tormenzembodying thisinvention and a por- --tion ;,of ammoldif or moldinga hollowtbody suchwas arconcrete duct.

Fig. 3 is a view similar to that shown in Fig. 2 but taken on the line33 of Fig. 1.

Fig. 4 is a View similar to Fig. 1 with the core former in a differentposition from that shown in Fig. 1.

Fig. 5 is a View similar to Figs. 1 and 4 with the core former in astill different position.

Fig. 6 is a detail perspective View of the core former with the spiralblade part separated from the wing member, and

Fig. '7 is a detail side View of a portion of the wing member andillustrates the different radii from the shaft of the difierent portionsof the cam compactor portion thereof.

While a core former embodying this invention may be used in connectionwithv any type of mold for forming the external surface of a moldedarticle such as a concrete duct, it is shown in Figs, 1, 2, 3, 4 and 5for purposes of illustration in connection with a mold for forming asquare duct and is peculiarly suited for use with a mold of thischaracter. The mold is indicated generallyby the reference character I0.It is preferred that the mold be of the type disclosed in my applicationSer. No. 93,786, filed August 1, 1936, for Apparatus and method formaking ducts (executed on even date herewith). In such case the mold It)comprises two portions, one portion of which is a master section II andthe other portion of which is a pallet I2. The master section and palletof the mold may be maintained in assembled relation by means of anysuitable clamping means such as a device comprising the V-shaped member[3 which carries at one end the link I4 hinged thereto by hinge l5. Atthe other end of the member 13 is a-hooked member l6. Parallel barmembers I! are hinged by hinge IE to both sides of the end of linkmember 14 and hinge pin means !9 carries block 20 between the barmembers I! so that the block 20 can be rotated about the axis of thehinge pin means I 9' relatively to the bar members I1. In screw threadedengagement with the block 20 is threaded rod 2| having an end 22 whichis adapted to rest in hooked end 23 of hook member l6. Projecting fromhook member [6 is a lug 24. By the means above described, the mastermold and pallet mold may be clamped together firmly and disassembledwhen desired as is more fully described in my said application Ser. No.93,786.

In use the mold l0 can be rested on a suitable support 25 and can bemaintained in proper position by suitable means (not shown) such as themeans shown and described in my said application Ser. No. 93,786. If thehollow molded form is to be a duct having male and female ends, a die 26may be used for forming the female end of the duct. This die may bestationary but is, preferably operatively connected to suitable means(not shown) for raising and lowering the die and for rotating the die.The

die 26 fits within an appropriate opening in the support 25. It is to beunderstoodthat any other suitable die may be used or that a die may beomitted altogether.

The device for shaping the other end of the duct is not shown herein butmay comprise apparatus of the character described in my application Ser.No. 93,787, filed August 1, 1936, for Apparatus for making ducts(executed on even date herewith). It is to be understood that any othersuitable die for shaping the top of the duct formed in the mold l0 mayalso be used or can be omitted. a .1

The core former to which this invention is particularly directed ismounted on shaft 30. It is to be understood that suitable means (notshown) are employed for rotating the shaft and for elevating andlowering the shaft. Moreover, it is to be understood that the shaft isadapted to be rotated by suitable means while the shaft is being raisedor lowered or while it is maintained at a constant level. Many types ofmeans for imparting the motion to shaft 30 which has been referred toabove are well known and for this reason require no description herein.

. Secured to the lower end of the shaft 30 in coaxial relation theretois a cylindrical head or follower 3!. The radius of the followernormally corresponds to the radius of the core which it is desired toproduce in the interior of the finished duct. The block 32 is alsosecured to the shaft 30. The follower 3| and the block 32 may be formedin one piece with shaft 30 L or may be made separately and assembled insecured relation thereto by suitable means (not shown) as may bedesired.

'Above the former head and mounted on the block 32 are wings or wingmembers indicated generally by the reference character 33. In theembodiment here shown, two wings 33 are employed. Each wing 33 has aninclined blade portion 34, a cam compactor portion positioned withreference to the shaft so as to have a troweling surface 36 that is at amaximum radius from the shaft 33 (which radius preferably issubstantially the same as the radius of the periphery of the follower3|). The cam surface presented by the cam compactor portion alsoincludes portions of lesser radius afiording a valley 35 immediatelyadjacent and alongside the blade portion 34 and between the bladeportion 34 and the follower 3|. This part of the wing is referred to asa cam compactor portion as it has a cam action on material in slidingcontact therewith, namely on the moldable material in the mold urging itoutwardly away from the axis of the shaft and against the mold partswhich form the external surfaces of the duct when the shaft is turned.The wing likewise has an upwardly tapering portion 3'! which serves apurpose referred to below. The wing also includes the base portion 38which overlies the follower 3| and has a radius correspondingsubstantially to the radius of the follower 3|. The valley 35 is deepestand widest adjacent the widest end of the wing 33 and becomes graduallyof decreased depth and width progressing toward the troweling surface36. Moreover, the upper end of the wing (and of the cam compactorportion thereof) is inclined as shown so that the cam compactor portionis immediately adjacent the inclined blade throughout a substantialperipheral distance of the blade and of the cam compactor portion.

Each of the wings 33 is mounted for adjustment to vary the radialdistance of the troweling surface of the wing (the portion thereof atthe greatest radial distance from the shaft) from the axis of the shaft.To this end the wing 33 has a recess 39 in the base portion 38, in thebottom of which is slot 40. A bolt 4i has its head in the recess 39 andextends through the slot 40 into an internally threaded part of theblock 32.

' By loosening the bolt 4!, the wing 33 can be slid into position andthe slot 40 permits a substantial amount of adjustment of the winglaterally of the shaft. When the wing member 33 is in .what is normallythe desired position, i. e., with the blade portion '34 or said '45 isnot subjected to anitiate the troweling, surface 36 in alignment 'withthe periphery of follower, the bolt can be tightened down so as to fixthe cam member in the selected position. The wing and particularly thetrowelhead 3|. As wear takes place on the troweling surface 36 so as toreduce its radius from the shaft, the wing can have its positionadjustedby loosening the bolt 40 and moving the wing 33 so that thetroweling surface36'thereof again comes into alignment with thecylindrical surface of the follower 3!.

A spiral blade part 45 is fixed to a sleeve 46 which is slidablelongitudinally with respect to the shaft 30. The sleeve 46 can bemaintained in any desired fixed position on a shaft 30 by tightening theset screw 51 one or more of which is carried by the sleeve 46 and isadapted to have its end forced into contact with the shaft 33. The end4'5 of the blade part 45 is adapted to abut the end 48 of the bladeportion 34 of one of the wings 33. In this manner the spiral blade part45 is made substantially continuous with I wing 33; 'and'the bladepart45 and inclined blade portion 34in effectare'parts of one continuousspiral blade. Normally it is preferable to have the pitch of the bladeportion 34 the same as that of the blade part 45 as shown'or at leastapproximately the same.

Theno mal working positions of the partsof the core former are shown inFigs. 1, 4 and 5. In Fig. 6 for purposes'of claritythe blade part 45 isshown moved upwardly on the shaft 33 so ,as to indicate how the spiralblade part '45can be moved into position with reference to wing 33 sothat the'end 4'Iof the bladepart"45 and the end 48 of the blade portion34 will be in abutting relation with respect to each other. It is alsoto be noted that the 'end 48 of'the blade portion'3 l of the wing33is ina plane corresponding to the plane of lateral movement afforded the wing33"on block 32. blade part 45 is in butting relationtothe'end 48 of'blade portion 34, the end4l will likewise be'in this plane. Thisarrangement enables the wing 33 to be adjusted with reference tofollower 3i (and withreference to theshaft so) inthe manner abovedescribed while still maintaining the ends M'and 48in abutting" relationwith reference to each other. I

The radius ofthe outside edgeof the spiral blade 45 is preferablysubstantially the same as the radius of the follower 3| and likewise thelongitudinal extent of blade 45 is preferably at least as great as thediameter thereof.

Apparatus made according to this invention can be used with only onewing'33. However, two wings 33 'are preferably employed as illustratedherein. In the device herein shown, the spiral blade part 45 can only bemade substantially continuous with the blade portion 34 of one of thewings 33. However, the second wing serves a purpose as it compacting andtroweling action moldable material such as concrete which has been actedupon by the other wing 33. Moreover; theseco ndwing 33 which does' nothave its blade portion 34 abutting the end of the spiralbladepart assevere wear as the other or first wing. After the first wing33"has*become When the end 4130f the serves to subject to a secondbadlyworn, the blade part 45 can be loosened on the shaft 30 and readjustedso that the end 41 thereof willcome'into abutting relation with the endof the blade portion of the second wing 33. This adjustment enables theapparatus to be used for substantially twice as long without renewingthe wings 33. While only one spiral blade part 45 is ordinarilycontemplated it would be possible in carrying out this invention to use'one spiral blade part 45 in connection with one wing 33 and a secondspiral blade part similar to spiral blade part 45 in connection with theother wing.

'In operation the core former can be used in any desired way. Forexample, the mold I0 can be assembled, clamped together and placed inposition in the support 25. The die 26, if used, is

placed in position at the bottom of the mold.

The core former on shaft 30 is then lowered to position adjacent the:bottom of the mold and is partially inserted in the hollow interiorportion of the die 26. C oncretelifl is then poured into the mold in amoist condition and the core former is caused to rotate and to beelevated through the concrete. Preferably the core former is elevatedsomewhat more slowly while it is adjacent the bottom of the moldtoinsure compacting of the material intoall parts of the female end to theduct being formed and the speed of rotation is controlled as desired. InFigs. 1, 4 and 5 the l core former is shown in different stages ofrotation and elevation, the follower 3|, in Fig. 5,

having been removed from the die 26, leaving a formed core 5| in theconcrete '60 (or other moldable material) in mold 10. The core formermay be eventually lifted out of the mold iii and the duct, having thecore 5 I ,can then be removed from the mold.

Compacting of the material in the mold is produced when the core formeris rotated in a coun 4 ter-clockwise direction in the apparatus shown inthe drawing and is: due to' the combined action of the spiral blade'andof the cam Compactor.

Of course, the parts can beinreverse direction so as to produce a likeeffect when the parts are rotated in a clockwise'direction. Moreover, asthe core former moves'upw'ardlywithin the mold, the tapered portion 31has a" still further compacting effect on materiahwithin the mold.During rotation of the core-former the moldable material 1 may be forcedby the spiral-blade into the valley 35 in the cam compactor portion ofthe wing 33 'at a time when the valley hasthe depth indicated at I inFig. '7. Upon rotation of the core former,

the material will slide inreference to the core former and will beforced to docupy the valley 35 when the depthhas decreased to that shownby line 2 in Fig. '7. Upon further "rotation of the core former, thedepth of the valley, which a particular portion of the materialoccupies, is

decreased as indicated by lines 3 and 4 in Fig. '7 and eventuallybecomes eliminated. At the same time the widthof the valley decreases asthe dotted linesl, 2, 3 and 4 also indicate which imparts a furthercompacting effect on the material. The material is then troweled by thetroweling surface presented by wing 33 and by the periphery of follower3!.

In connection with a core former'constructed in the manner hereinillustrated and described,

it is significant thatthe spiral blade and cam compactor portions are inendwise juxtaposition. The moldable material, e. g.'concrete, is insliding contact with the'spiral blade and material on a surface thereoftoward the cam compactor is' urged toward the cam compactor uponrotation of the shaft in a given direction. Without interruption of thecompacting force the material is brought into sliding contact with thecam compactor which then urges the material outwardly from the shaft andtoward the wall of the mold. This results in the building up of highpressures on the concrete so that even the remote parts in the angles ofsquare molds are filled and furthermore the compacting is at all timesuniform so that there are not portions of concrete 0f varyingconsolidations within the mold. In previous devices neither the degreeof pressure nor the uniformity thereof in different parts of the moldwas sufficient to avoid a large percentage of rejectable ducts. Inconnection with this aspect of this invention, it may be said that if aspiral blade is used which is independent of and is substantiallyseparated from a cam compactor, the results obtainable are very muchinferior both in degree of compacting and in uniformity of compacting.With the core former embodying this invention rejections of ductsbecause of poor consolidation has been substantially eliminated andducts of substantially higher strength as a whole and uniformitythroughout and of substantially improved structure are obtainable.

It may also be noted that the spiral blade including blade portion 34 ofwing 33 is so positioned in endwise juxtaposition to the cam compactorportion of the wing 33 that it terminates in that part of the winghaving greatest radius from the shaft, namely, above troweling surface36 of the wing 33. This causes the portions of different radius from theshaft of the cam surface presented by the wing 33 to be immediatelyalongside the blade portion 34 so as to augment the combined downwardand outward compressive forces acting in the material in the mold.Likewise the cam compactor portion is not only decreased in depth butalso is decreased in width progressing downward the portion of the winghaving greatest radius from the shaft so as to further augment thewedging and compacting of the material in the mold, before it is finallytroweled and smoothed by the follower 3|.

The foregoing desirable effects, can, according to this invention, besecured in a core former in which the parts can be readily adjusted andin which the more rapidly wearing parts can be readily renewed. In thisconnection the adjustability of the wing 33 with reference to thefollower 3! while maintaining desired relation between the wing 33 andthe blade part 45 is to be observed. The construction of the spiralblade so as to be partly on a blade part and partly on an adjustablewing contributes to this feature. Other desirable features relate to thefacility with which the wings 33 and the spiral blade part 45 cannotonly'be adjusted but completely removed and be replaced when desired.

It is to be understood that the embodiment of this invention which hasbeen shown and described hereinabove is illustrative merely and thatapparatus embodying this invention may take various forms. Accordinglythe scope of this invention is to be limited only by the language ofthe, following claims.

I claim:

1. In apparatus of the character described, a core former adapted toform the core of a concrete duct, which comprises a. shaft, a camcompactor in secured relation to said shaft presenting a cam surfaceadapted to urge material in sliding contact therewith outwardly awayfrom said shaft pactor in secured relation to said shaft presenting acam surface adapted to urge material in sliding contact therewithoutwardly away from said shaft upon rotation of said shaft in a givendirection, and a spiral blade disposed about said shaft in securedrelation thereto adapted to urge material in sliding contact with asurface thereof facing said cam compactor toward said cam compactor uponrotation of said shaft in said direction, said spiral blade and camcompactor being in substantially immediate endwise abutment on saidshaft, the radial distance of the end of the outer edge of said bladebeing substantially the same as the greatest radial dimension of saidcam compactor.

3. In apparatus of the character described, a core former adapted toform the core of a concrete duct, which comprises a shaft, a camcompactor in secured relation to said shaft presenting a cam surfaceadapted to urge material in sliding contact therewith outwardly awayfrom said shaft upon rotation of said shaft in a given direction, aspiral blade disposed in endwise juxtaposition to said cam compactorabout said shaft in secured relation thereto and adapted to urgematerial in sliding contact with a surface thereof facing said camcompactor toward said cam compactor upon rotation of said shaft in saiddirection, said cam compactor having the end portion toward said spiralblade inclined to. correspond at least approximately to the pitch ofsaid spiral blade so that the said cam surface throughout a substantialperipheral extent thereof about said shaft is immediately adjacent saidspiral blade throughout a substantial portion of the length of saidblade.

4. In apparatus of the character described, a

core former adapted to form the core of a concrete duct which comprisesa shaft, a cam compactor in secured relation to said shaft presenting acam surface adapted to urge material in sliding contact therewithoutwardly away from said shaft upon rotation of said shaft about itsaxis in a given direction, a spiral blade disposed in endwisejuxtaposition to said cam compactor about said shaft in secured relationthereto and adapted to urge material in sliding contact with a surfacethereof facing said cam compactor toward said cam compactor uponrotation of said shaft about its axis in said direction, a cylindricalfollower in coaxial secured relation with said shaft and in endwisejuxtaposition with the end of said cam compactor remote from said spiralblade, said cam surface having its maximum distance radially from saidshaft about the same as the radial distance from the axis of said shaftof the periphery of said follower and affording throughout at least apart of the peripheral length thereof a valley between said blade andsaid follower which diminishes in depth and in width progressing towardthe portion of said cam sursaid shaft.

5. In apparatus of'the character described, a core former adapted toformthe core of a concrete duct which comprises a shaft, a cylindricalfollower in coaxial secured relation to said shaft, a spiral blade partdisposed about said shaft in secured relation thereto adapted to urgematerial in sliding contact with a surface thereof facing said followertoward'saidfollower upon rotation of said shaft about its axis in agiven direction, and a wing member interposed in endwise juxtaposedposition between said follower and said spiral blade part, said wingmember having a blade portion at the end thereof adjacent said spiralblade part which has a pitch corresponding at least approximately to thepitch of said spiral blade part and having a cam compactor portionbetween said blade portion and said follower which is adapted to urgematerial in sliding contact therewith outwardly away from the axis ofsaid shaft upon rotation of said shaft about its axis in said direction.

6. In apparatus of the character described, a core former adapted toform the core of a concrete duct which comprises a shaft, a cylindricalfollower in coaxial secure-d relation to said shaft, a spiral blade partdisposed about said shaft in secured relation thereto and adapted tourge material in sliding contact with a surface thereof facing saidfollower toward said follower when said shaft is rotated about its axisin a given direction, and a wing member interposed in endwise juxtaposedrelation between said follower and said spiral blade part, said wingmember having a blade portion with its end adjacent said spiral bladepart in abutting relation with respect to the end of the said spiralblade part and with a pitch corresponding at least approximately to thepitch of said spiral blade part and having a cam compactor portionbetween said follower and said blade portion presenting a cam surfaceadapted to urge material in sliding contact therewith outwardly fromsaid shaft upon rotation of said shaft in said direction about its axisand a troweling surface adapted to smooth the outwardly urged material,means affording said wing member movement laterally of said shaft whilemaintaining the end of said blade portion thereof in substantiallyabutting relation with respect to the end of said blade part to vary theradial distance from said shaft of said troweling surface, and means formaintaining said wing member in secured relation with respect to saidshaft in a plurality of different positions afforded by said movement.

7. In apparatus of the character described, a core former adapted toform the core of a concrete duct which comprises a shaft, a sleeve aboutsaid shaft in slidable relation therewith, means for fastening saidsleeve to said shaft, a spiral blade part disposed about and secured tosaid sleeve, a cylindrical follower in coaxial secured relation to saidshaft, a block in secured relation to said shaft between said followerand said sleeve, and a wing member presenting a cam surface adapted tourge material in sliding contact therewith outwardly away from the axisof said shaft when said shaft is rotated about its axis in a givendirection, said wing member being mounted for adjustment laterally ofsaid shaft on said block to vary the maximum radial distance of said camsurface from said. shaft, and said spiral blade part being adapted tourge material in sliding contact with a surface thereof facing said wingmember toward said wing member.

8. In apparatus of the character described, a core former adapted toform the core of a concrete duct which comprises ashaft, a sleeve aboutsaid shaft in -secured relation thereto,a spiral blade part disposedabout and secured to said sleeve, a cylindricalfollower in coaxialsecured relation to said shaft, a block in secured relation to saidshaft between said follower and said sleeve, a wing member includingablade portion having" a pitch corresponding at least approximately tothe pitchofsaid spiral blade part and a cam compactor portion presentinga cam surface adapted to urge material in sliding contact therewithoutwardly from the axis of said shaft when said shaft is rotated aboutits axis in a given direction and means for mounting said wing member onsaid block with the end of said blade portion thereof abutting the endof said spiral blade for adjustment of the alignment of the portion ofsaid cam surface at maximum radial distance from the axis of said shaftwith reference to the peripheral surface of said follower, said spiralblade part being adapted to urge material in sliding contact with asurface thereof facing said wing member toward said wing member uponrotation of said shaft about its axis in said direction.

9. In apparatus of the character described a core former adapted to formthe core of a concrete duct, which comprises a shaft, a cam compactorpresenting a cam surface adapted to urge material in sliding contacttherewith outwardly away from said shaft upon rotation of said shaftabout its axis in a given direction and a troweling surface adapted tosmooth the outwardly urged material, a spiral blade part disposed aboutsaid shaft detachably and adapted to urge material in sliding contactwith a surface thereof facing said cam compactor toward said camcompactor upon rotation of said shaft in said direction about its axis,means for mounting said cam compactor for adjustment to vary the radialdistance from said shaft of said troweling surface, and means formounting said spiral blade on said shaft for adjustment to vary thelongitudinal position of said spiral blade on said shaft.

10. In combination with a core former mounted on a shaft and adapted toform the core of a concrete duct, compacting means comprising aninclined blade part and a cam compactor part, I

said inclined blade part upon rotation of said core former about itsaxis in a given direction being adapted to urge material in slidingcontact with a surface thereof facing said cam compactor partlongitudinally of said shaft toward said cam compactor part, and saidcam compactor part presenting a cam surface immediately alongside saidinclined blade part throughout a substantial portion of the length ofsaid blade part.

adapted to urge material in sliding contacttherewith outwardly away fromsaid shaft upon rotation of said shaft about its axis in said directionso that said material is urged outwardly by said cam surfacesimultaneously with being urged longitudinally by said spiral blade partupon rotation of said shaft.

11. In apparatus of the character described a core former adapted toform the core of a concrete duct which comprises a shaft, a wing memberincluding a cam compactor portion presenting a cam surface adapted tourge material in sliding contact therewith outwardly from said shaftupon rotation of said shaft about its axis in a given direction and aninclined blade portion adjacent an end thereof adapted to urge its axisin said direction, and said wing member being mounted on said shaft withthe end of said blade portion carried by said wing member abutting saidend of said blade part, and means for adjusting said wing member to varythe 5 maximum radial distance of said cam surface from said shaft whilemaintaining said end of said spiral blade part abutting said end of saidblade part carried by said wing. member.

HINIS OROURKE.

